Agreed. In the old world, this is what an alpha/beta/gamma environment could help test against. The in memory could be used to make sure your units and overall components were correctly specified. The actual installs of the DB software to isolated schemas were where you made sure you integrated with the DB correctly.

That all said, I did not mean this to be that Docker doesn't provide some value. Just pointing out it is not a prerequisite. If that makes sense.